U.S. Pat. Nos. 4,122,274 and 4,209,620 describe the antiallergic agents 3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-ones and methods for their synthesis. Unfortunately, the methods disclosed therein are not particularly convenient since they generally require several steps and/or the use of complex procedures and/or dangerous reactants such as azides.
Ethyl tetrazol-5-ylacetate is described by Finnegan, et al., J. Am. Chem. Soc., 80,3908 (1958). It is used to prepare 5-phenyltetrazole and various other substituted tetrazoles.